@AmaigaDragon:
I suppose it depends on how well organized the assassin has hidden their weapons. I wish I could queue up footage, since it was fun as all heck the first time I saw it on hulu, in the anime bakemonogatori one of the main characters for the first episode has hidden something to the effect of an office supply store on her person... which is ironic because she supposedly only weighs 5kg... and then there is mousse from Ranma who uses Shaolin hidden weapons techniques
There was also a talk show from maybe 10 years ago that showed in real life how impressively a typical teenage boy could smuggle in maybe 22guns on their person without a backpack... granted one of those guns was a shotgun he smuggled down his pants and the exercise sort of lost it's credibility. The footage below is not nearly as impressive.
http://www.youtube.com/watch?v=TMA2zkodZCk I probably got flagged by the government for looking up hidden weapons so this video comes at a price I'm sure.
We're also assuming he isn't using some sort of frost magic to create the caltrops or that he didn't prepare them while he was waiting.
